It's not like a pile either but I think more like a network of associations, a mesh. When you hear chess grandmasters talk, they don't go by "the rook is worth 5 and the knight is worth 3 points" or some neat system, they trust on intuition that often brings together particular positions, old games, calculation and so on. Just like an expert programmer doesn't sit there with her copy of the Gang of Four in hand.
Experts often don't really think as much as they simply do, and they're process oriented. Which I think is also more important to teach.
That's exactly the point. Their knowledge has some organization and structure, it's not just random pile of information. The author is advocating that we help people to organize information so that it is more useful to them. They even go so far as saying to try understanding how the person models other thing to leverage that. In other words, the closet thing is a metaphor, but also can be a starting point.